1. Field of the Invention
The present disclosure relates to a magnetic contactor, and more particularly, to a magnetic coil assembly for the magnetic contactor.
2. Description of the Conventional Art
Referring to FIG. 1, in general, the externally exposed portion of a magnetic contactor 100 may be largely divided into an upper frame 10 and a lower frame 20.
A typical magnetic contactor 100 in FIG. 1 may include a fixed core 1, a movable core 4, a coil 33, a bobbin 31, a cross bar 8, a movable contact 6, stationary contact 7, and a return spring 9, which are accommodated into the upper frame 10 and lower frame 20, referring to FIG. 2 as an internal configuration.
The fixed core 1 may be fixed and provided at an internal bottom surface of the lower frame 20, and configured with a divided “E”-shaped iron core. The bobbin 31 may be inserted into a central portion of the “E”-shaped fixed core 1, and the coil 33 may be wound around the bobbin 31. Accordingly, the fixed core 1 is magnetized while magnetizing the coil 33 when electrical current flows into the coil 33 of the bobbin 31 being inserted into the central portion, and the fixed core 1 is demagnetized when the flow of electrical current flowing into the coil 33 is terminated.
The movable core 4 may be provided in a vertically movable manner at an upper portion facing the fixed core 1, and the return spring 9 may be normally provided between the bobbin 31 and movable core 4 to exert an elastic force to the movable core 4 in the direction of leaving from the fixed core 1, namely, in an upward direction in FIG. 2.
The cross bar 8 may be combined with the movable core 4 integrally at an upper portion of the movable core 4, thereby allowing them to be movably provided together in a vertical direction. Three movable contacts 6 corresponding to alternating current three-phases(three-poles) are installed at the cross bar 8 to be supported by the cross bar 8, allowing the movable cross bar 8 to be moved together, and three stationary contacts 7 corresponding to alternating current three-phases are provided in a fixed manner at a position facing the movable contact 6. The operation is of a typical magnetic contactor 100 having the foregoing configuration will be described in brief with reference to FIG. 2.
Referring to FIGS. 3 and 4, if a control signal is applied to terminals 32a, 32b which will be described later, then the fixed core 1 is magnetized as a current of the control signal flows into the coil 33, and therefore, the movable core 4 and cross bar 8 move downward while overcoming an elastic force of the return spring 9 in FIG. 2 as the facing movable core 4 is attracted by a magnetic force, thereby allowing a bottom surface of the movable core 4 and an upper surface of the fixed core 1 to be brought into contact with each other. At this time, the movable contact 6 being supported by the cross bar 8 is brought into contact with the corresponding stationary contact 7. Accordingly, when an electric power source and a motor are connected to the stationary contact 7, the electric power is supplied to the motor from the electric power source by the magnetic contactor.
If the application of a control signal to terminals 32a, 32b which will be described later is terminated with reference to FIGS. 3 and 4, then the fixed core 1 is demagnetized as a current does not flow into the coil 33, and therefore, the facing movable core 4 is separated from the fixed core 1 by an elastic force of the return spring 9. At this time, the movable contact 6 being supported by the cross bar 8 is separated from the corresponding stationary contact 7. Accordingly, when the electric power source and the motor are connected to the stationary contact 7, the electric power supplied to the motor from the electric power source is broken by the magnetic contactor.
A magnetic coil assembly providing a driving force of the movable core 4 in the foregoing magnetic contactor 100 according to an example of the related art will be described with reference to FIGS. 3 and 4.
FIG. 3 is a perspective view illustrating a magnetic coil assembly in a state that a coil is not wound in a magnetic coil assembly according to the related art, and FIG. 4 is a perspective view illustrating a magnetic coil assembly in a state that a coil is wound in a magnetic coil assembly according to the related art. As illustrated in the drawing, a magnetic coil assembly 30 according to the related art is largely divided into a bobbin 31, terminals 32a, 32b, and a coil 33.
Referring to FIG. 3, the bobbin 31 is made of an electrical insulating material such as synthetic resin, and typically may include a square pillar shaped body portion having an internal hollow portion and flange portions formed at both end portions in a length direction of the body portion. An upper flange portion of the flange portions may include a pair of extension portions extended lengthways in one direction to install the terminals 32a, 32b, and an insulating partition portion for electrically insulating the both terminals 32a, 32b from each other and from the other elements of the magnetic contactor. The extension portion may have a terminal supporting groove portion extended by a predetermined gap to press and support the body portion of terminals 32a, 32b therebetween.
The terminals 32a, 32b are made of an electrical conductor connected to a conducting wire that provides the control signal of the magnetic contactor 100, and may include a head portion for connecting a wire which is easily seen in FIG. 3, a elongate body portion extended from the head portion, and a first coil fixing protrusion portion 32a-1 bent at a right angle in a horizontal direction from the body portion to be connected with a starting end portion of the wound coil 33.
A connection between the coil 33 and first coil fixing protrusion portion 32a-1 and their connection maintenance may be typically achieved using the method of winding a starting end portion of the coil 33 around the first coil fixing protrusion portion 32a-1 with one or two turns and then soldering and fixing it.
The terminal 32b also has a configuration similar to the terminal 32a which is easily seen in FIG. 3, and may include a head portion for connecting a wire, a elongate body portion extended from the head portion, and a terminating coil connecting end portion (not shown) bent at a right angle in a horizontal direction from the body portion to be connected with an terminal end portion of the wound coil 33.
The method of winding the coil 33 around the bobbin 31 may be achieved by connecting and rotating the bobbin with a power transmission shaft of a motor in a state that the starting end portion is connected and fixed to the first coil fixing protrusion portion 32a-1 as described above. At this time, the number of rotations of the motor, i.e., bobbin, is proportional to the amount of coil wrapped around the bobbin, and a time for winding the coil increases as increasing the amount of coil being wrapped. As a result, when a winding time is reduced by increasing the rotation speed of the motor, it may cause a problem of broken wire while winding the coil.